Empirical studies of the relationships between alcohol outlets, alcohol use and related problems have demonstrated that greater outlet densities are related to drinking and alcohol-related problems among adults. The literature on alcohol outlets, youth alcohol use and related-problems is not as developed but indicates that underage youth may purchase alcohol themselves (usually from off-premise outlets), arrange purchases through others, or obtain alcohol by other social means. Among these modes of access to alcohol, direct underage purchases are often successful. If densities of alcohol outlets affect the likelihood that underage youth will successfully purchase alcohol, then regulation of these outlets may be a useful strategy to control underage sales. The proposed research seeks to answer three questions: (1) Does the physical availability of alcohol affect the distribution of alcohol-related problems among young people? (2) Does the physical availability of alcohol affect the distribution of alcohol-related arrests among young people? (3) Does the physical availability of alcohol affect patterns of youth access to alcohol? These questions will be answered through geostatistical analyses of archival data from the state of California and multilevel analyses of individual survey data from areas of the state with high, average and low off-premise outlet densities. Study #1 will examine the spatial and temporal relationships between youth population distributions, retail market areas, alcohol outlet densities, and hospitalizations related to youth use of alcohol across approximately 1,493 zip code areas over 13 years. Study #2 will examine the spatial and temporal relationships between youth population distributions, retail market areas, alcohol outlet densities, and arrests related to youth use of alcohol for about 413 police jurisdictions over 13 years. Study #3 will use a geographically based multilevel model to examine the effects of outlet densities and local population characteristics on self-reported patterns of youth access to alcohol. The goals of the study are to understand the mechanisms by which alcohol outlets may affect underage sales and related problems and to provide an assessment of the effects of outlets on youth problems.